Sulphonated, aromatic reaction products, processes for their manufacture and their use as substances having a tanning action

ABSTRACT

The invention relates to sulphonated, aromatic reaction products as agents for tanning hides and leather. They are obtained by reacting a sulphonation product, which is previously formed from a diphenyl ether, a phenol and a sulphonating agent, with formaldehyde, with a reaction mixture of an aminoplast-forming agent and formaldehyde or with an aminoplast precondensate.

The invention relates to sulphonated, aromatic reaction products of

(1) 100 PARTS BY WEIGHT OF A SULPHONATION PRODUCT OF

(A) 10 to 90 percent by weight of at least one diphenyl ether which isoptionally substituted by methyl,

(B) 90 to 10 percent by weight of at least one phenol which isoptionally substituted by methyl, the sum of components (A) and (B)being 1 mol, and

(C) 1 to 2 mols, calculated as sulphuric acid, of a sulphonating agentand

(2) 1 TO 6 PARTS BY WEIGHT OF FORMALDEHYDE OR OF A FORMALDEHYDE DONOR OR

(3) 4 TO 24 PARTS BY WEIGHT OF A REACTION MIXTURE CONSISTING OF

(D) at least one aminoplast-forming agent and

(E) formaldehyde or a formaldehyde donor, or

(4) 4 TO 24 PARTS BY WEIGHT OF AT LEAST ONE AMINOPLAST PRECONDENSATE.

The reaction products according to the invention have always beenmanufactured from component (1), which itself has previously been formedfrom components (A), (B) and (C), and one of the components (2), (3) or(4). The reaction products obtained from components (1) and (2) are lesspreferred. The most preferred reaction products are those obtained fromcomponents (1) and (4) and especially those obtained from components (1)and (3).

Further preferred reaction products are those obtained from 100 parts byweight of component (1) and 2 to 5 parts by weight of component (2) andespecially from 100 parts by weight of component (1) and 9 to 15 partsby weight of component (4) or, in particular, (3).

Components (1) which can be used are, above all, those which havepreviously been formed from 20 to 75, and especially 60 to 70, percentby weight of component (A) and 80 to 25, and especially 40 to 30,percent by weight of component (B), the sum of components (A) and (B)being 100 percent by weight, and from 1.05 to 1.50, and especially 1.15to 1.35, mols of component (C), the sum of components (A) and (B) being1 mol. A particularly interesting component (1) has been pre-formed, forexample, from a mixture of 70 parts by weight of component (A) and 30parts by weight of component (B), the sum of components (A) and (B)being 1 mol, and 1.3 mols of component (C).

An aqueous formaldehyde solution can be used, above all, as component(2) or (E). Possible formaldehyde donors, which can be used in place offormaldehyde, which is preferred, are, inter alia, trioxane or, inparticular, paraformaldehyde. The abovementioned proportions of 1 to 6parts by weight of component (2) or 4 to 24 parts by weight of component(3) per 100 parts by weight of component (B 1) and of 1 to 3 mols ofcomponent (E) per 1 mol of component (D) are always relative toformaldehyde. When a formaldehyde donor, such as trioxane or, inparticular, paraformaldehyde, is employed, the quantities of theformaldehyde donor must be adjusted in accordance with the formaldehydewhich is actually released.

Preferred components (3) consist of 1 mol of component (D) and 1 to 3,especially 2, mols of component (E) and preferred components (4) consistof aminoplast precondensates which are mono-, di- or tri-methylolatedand preferably dimethylolated.

Components (A) and (B) which can be used are, above all, those which areoptionally substituted by at most 4 methyl groups. Accordingly,preferred components (A) consist, for example, of a dixylyl ether, aboveall of diphenyl ether or in particular of a ditolyl ether and preferredcomponents (B) consist, for example, of a xylenol, above all of a cresolor in particular of phenol. Industrial mixtures of isomers are ofprimary interest as dixylyl ethers, xylenol and, in particular, ofditolyl ethers and cresol. Components (A) and (B) can also be in theform of mixtures of the compounds mentioned, these mixtures being lesspreferred.

Preferred components (C) consist of oleum or, in particular, ofsulphuric acid monohydrate. Oleum which can be used is, above all, oleumwhich contains 20 percent by weight of SO₃. Mixtures of technical grade,for example 94 percent strength by weight, sulphuric acid and preferably20 percent strength by weight oleum, and above all mixtures consistingof sulphuric acid to which oleum has been added in an amount such that a100 percent strength by weight sulphuric acid, that is to say sulphuricacid monohydrate, is formed, can also be used.

The aminoplast-forming agents, which in the unmethylolated form areemployed as component (D), are nitrogen compounds which can bemethylolated. The addition products of formaldehyde and these nitrogencompounds which can be methylolated, that is to say aminoplast-formingagents, are generally known as so-called aminoplast precondensates andare employed as component (4).

Examples of aminoplast-forming agents which may be mentioned aretriazine, melamine, triazone, urone, cyanuric acid, acetoguanamide(2,4-dihydroxy-6-methyl-1,3,5-triazine), acetoguanide(2-amino-4-hydroxy-6-methyl-1,3,5-triazine), formoguanamine(2,4-diamino-1,3,5-triazine), ammelide(2,4-dihydroxy-6-amino-1,3,5-triazine) and ammeline(2,4-diamino-6-hydroxy-1,3,5-triazine). Aminoplast-forming agents whichhave at most 4 nitrogen atoms, such as acetylenediurea, urethane orcyanamide, are also preferred. The most preferred compounds are urea andthe so-called urea derivatives, especially those which contain 2 or 3nitrogen atoms and a single structural element of the formula ##STR1##such as, for example, oxadiazine (1-oxo-4-keto-3,5-diazine),propyleneurea, dihydroxyethyleneurea, ethyleneurea, biuret, thiourea andguanidine. Compounds of primary interest here are above all biuret andespecially urea.

Preferred components (D) consist of thiourea, ethyleneurea, preferablybiuret and in particular urea and preferred components (4) consist ofthe corresponding mono-, di- or tri-methylolated aminoplastprecondensates and especially of the corresponding dimethylolatedaminoplast precondensates. Mixtures of the said aminoplast-formingagents or aminoplast precondensates can also be used as components (D)or (4). Compounds of primary interest are urea on its own as component(D) and dimethylolurea on its own as component (4).

Component (4) can also be formed in situ by adding component (3), thatis to say components (D) and (E), to the reaction mixture.

The reaction products according to the invention are manufactured byfirst reacting components (A), (B) and (C) with one another at elevatedtemperature, then further reacting the sulphonation product, which isthus obtained, as component (1) with one of the components (2), (3) or(4) at elevated temperature, subsequently adding an organic or,preferably, inorganic base to the reaction product which is thusobtained and then optionally adding an organic acid. This manufacturingprocess for the reaction products according to the invention thus alsoconstitutes a subject of the present invention.

The reaction of components (A), (B) and (C) is preferably carried out inthe melt at 110° to 180° C. At temperatures below 110° C. the reactionproceeds too slowly, whilst temperatures above 180° C. effect anundesired dark colouration of component (1). As a rule, the reaction isstarted under normal pressure at 110° to 140° C., and preferably 120° to135° C., and the sulphonation mixture is kept at this temperature for 2to 3 hours. The temperature is then preferably raised to 145° to 170° C.and the water formed during the reaction is appropriately removed undera reduced pressure of 10 to 20, and especially 12 to 15, mm Hg. In ausual case, the sulphonation reaction has ended after a reaction time of2 to 10, and especially 3 to 5, hours.

The sulphonation reaction can be followed by titrating samples of thereaction mixture, which have been diluted with water, with an aqueoussodium hydroxide solution. The consumption, in milliliters, of 1.0 Nsodium hydroxide required to adjust the pH value of 1 g of the reactionmixture to 3.5 is termed the acid number. The sulphonation reaction hasended as soon as the acid titre of the reaction mixture no longerdecreases and remains constant. The decrease in the acid titre duringthe sulphonation reaction indicates that the sulphonation productsundergo a partial condensation reaction with themselves, that is to saythat partial auto-condensation takes place, some of the free sulphogroups --SO₃ H of the sulphonation products being converted to sulphonebridges --SO₂ -- in the auto-condensation products. After the reactionhas ended, the acid titre is as a rule 3.0 to 5.5 especially 4.0 to 4.6.

In the usual case, reaction components (A), (B) and (C) are all heatedto 110° to 180° C. at the same time. However, it is also appropriatefirst to heat up component (A) or, preferably, (B) with component (C) to110° to 120° C. and then to add component (B) or, preferably, (A) andonly then to heat the reaction mixture to 110° to 180° C.

The reaction of component (1), which is thus obtained, with one of thecomponents (2), (3) or (4) is preferably carried out at 60° to 95° C.Appropriately, the resulting hot sulphonation mixture, as component (1),is cooled to 75° to 95° C. and preferably diluted with water, and one ofthe components (2), (3) or (4), which as a rule are in the form ofaqueous solutions, is added. In the usual case the reaction time is 2 to20, and especially 3 to 6, hours.

Although component (1) can be stored, it is most appropriate and mosteconomical to carry out the reaction of component (1) with one of thecomponents (2), (3) or (4) in the same reaction vessel by the so-calledone-pot process, without isolation of any intermediate product.

For working-up, an organic or, preferably, inorganic base is added tothe resulting reaction product.

Organic bases employed are tertiary, secondary and, above all, primaryalkylamines or alkanolamines with 1 to 6 carbon atoms and in particularethanolamines. Tri-, di- or mono-methylamine, in particular tri-, di- ormono-ethylamine and especially tri-, di- or mono-ethanolamine arepreferred.

Inorganic bases employed are alkaline earth metal hydroxides or, aboveall, alkali metal hydroxides. Magnesium hydroxide and, above all,potassium hydroxide or sodium hydroxide are preferred and concentratedaqueous solutions are of primary interest. A particularly suitableinorganic base is ammonia, above all in the form of a concentratedaqueous solution.

The pH value of the reaction products, which are in the form ofconcentrated aqueous solutions, is adjusted to 3 to 7, and preferably 3to 4, by the addition of the abovementioned bases.

Tri-, di- and, above all, mono-carboxylic acids with 1 to 6 carbon atomscan be used as organic acids, which are optionally added to the reactionproducts. A preferred tricarboxylic acid is, inter alia, citric acid.Maleic acid and oxalic acid may be mentioned as examples of furtherpreferred dicarboxylic acids. Examples which may be mentioned of themost preferred monocarboxylic acids are lactic acid, acetic acid andformic acid, acetic acid and, in particular, formic acid being ofprimary interest.

On the addition of the abovementioned acids, the pH value of thereaction products, which are in the form of concentrated aqueoussolutions, falls from the original value of 3 to 7, and preferably 3 to4, after the addition of the base, to 2.5 to 3.5 after the addition ofthe acid.

The reaction products are as a rule in the form of ready-to-use,aqueous, viscous, syrupy solutions which have a solids content ofpreferably 30 to 60 percent by weight and especially 40 to 55 percent byweight. However, it can also be advantageous to evaporate the aqueoussolutions of the reaction products, for example at 70° to 80° C. underreduced pressure, to give a solid form, inter alia by spray-drying or byforming granules. The solid reaction products preferably have a solidscontent of 90 to 100, and especially 96 to 100, percent by weight. Boththe syrupy reaction products and the solid reaction products are solublein water. If the reaction products are obtained in a solid form, theoptional addition of the organic acids can appropriately be carried outprior to evaporation of the aqueous solutions. The organic acid can,however, also be mixed into the reaction product, which is preferably inthe form of a powder.

The precise chemical constitution of the reaction products according tothe invention can be characterised only by their mode of manufacture.Nevertheless, on the basis of the acid titre which is obtained forcomponent (1), it can be assumed that probably 10 to 40% of the freesulpho groups have been converted into sulphone bridges.

The new, sulphonated, aromatic reaction products according to theinvention are used as substances which have a tanning action. The use ofthese reaction products is thus also a subject of the present invention.

Analysis of the reaction products according to the invention todetermine the tanning agent content is carried out by the filter processof the VGCT (Verein fur Gerbereichemie und Technik (Association forTanning Chemistry and Technology)) (in this context compare "Das Leder"5 [2], 28 to 31 (1954)).

The reaction products according to the invention, which have a tanningaction, are suitable for tanning or re-tanning all types of hides andleather. Reaction products to which no acid has been added arepreferably used for leathers which have not been neutralised. Reactionproducts of this type have a preferred pH value of 5 to 7 after theaddition of the base. The reaction products to which an organic acid hasbeen added are preferably used for tanning hides or for re-tanningneutralised leathers. In this case, the reaction products, the pH valueof which has been adjusted to preferably 3 to 4 by the addition of thebases, have preferred pH values of 2.5 to 3.5 after the addition of theacid.

In order to achieve a good filling effect and buffability of the treatedleather, the reaction products according to the invention can, forre-tanning leather, be used in the presence of at least onelignin-sulphonic acid salt, such as is obtained from the isolation ofcellulose, and/or albumin glue, such as glutin glue or gelatine.

The reaction products according to the invention can also be used at thesame time as tanning agents, fillers and/or bleaching agents for chromeleather.

Further subjects of the present invention thus relate to agents fortanning or re-tanning hides and leather, which contain at least onereaction product of the composition indicated above, a process fortanning or re-tanning hides and leathers with at least one such reactionproduct and hides or leather tanned or re-tanned by this process.

In agents for re-tanning leather, which contain lignin-sulphonic acidsalts and/or albumin glues in addition to the reaction productsaccording to the invention, the content of the reaction productsemployed is at least as great as the content of the additives mentioned.

When tanning or re-tanning hides or leather, the procedure isappropriately such that hides or leather are treated with an aqueoussolution containing at least one reaction product according to theinvention and the material tanned in this way is rinsed and then stuffedand dried. If desired, dyeing can be carried out prior to stuffing.

As a rule, 100 to 200, and preferably 150 to 200, parts by weight ofwater and 1 to 32 parts by weight, calculated relative to the drysubstance, of at least one of the reaction products according to theinvention are employed per 100 parts by weight of leather or hide.

In particular, 100 parts by weight of delimed pelt are tanned with 150to 200 parts by weight of water and 12 to 32 parts by weight of one ofthe reaction products according to the invention. The reaction productswhich have a pH value which has been adjusted to 2.5 to 3.5 with anorganic acid are preferred for this purpose. The use of reactionproducts to which no acid has been added and which have a pH value of 5to 7 after the addition of the bases is also possible if the pH value ofthe tanning bath is adjusted to 3.2 to 4.0 with an organic acid, forexample formic acid.

In particular, 100 parts by weight of chrome-tanned leather which hasbeen neutralised in the customary manner using, for example, formates orbicarbonates, are re-tanned with 1 to 16, and preferably 1 to 8, partsby weight of one of the reaction products and optionally with at most anequal amount of a lignin-sulphonic acid salt and/or of an albumin gluein aqueous solution. Above all, reaction products which contain anorganic acid are employed for this purpose.

The tanned material is rinsed and then stuffed with a customary stuffingagent which is preferably fast to light and is based on, for example,sulphonated sperm oil or neats' foot oil.

After drying, this gives a white or very pale leather which hasexcellent fastness to light, a fine, compact, smooth grain and a softhandle. The strong bleaching effect achieved on re-tanning is especiallyadvantageous, in particular on chrome leather.

The percentages and parts in the Examples which follow are parts byweight and percentages by weight. The relationship between parts byvolume and parts by weight is the same as that between ml and g.

EXAMPLE 1

300 parts of ditolyl ether (1.51 mols of a mixture of isomers) and 500parts (5.31 mols) of phenol are mixed and sulphonated with 765 parts of20% oleum (corresponding to 8.15 mols of sulphuric acid) at 125° to 130°C. for 3 hours. The mixture of sulphonic acids is now heated to 160° C.under a reduced pressure of 15 mm Hg for 5 hours. After this time theacid titre no longer changes and is 4.3. In order to determine the acidtitre, a sample of the resulting mixture of sulphonic acids is dilutedwith water and titrated against an aqueous 1.0 N solution of sodiumhydroxide using Congo red as the indicator.

100 parts of the mixture of sulphonic acids are dissolved in 20 parts ofwater. 5 parts of a 30% strength aqueous solution of formaldehyde areallowed to run into the solution at 80° to 85° C. The condensationreaction is continued for 2 hours at the same temperature. After adding85 parts of water, the pH of the reaction solution is adjusted to 4.0with 44 parts of a 25% strength aqueous solution of ammonia andsubsequently 6 parts of an 85% strength formic acid are added.

255 parts of a red-brown coloured syrup of low viscosity which dissolvesin water to give a clear solution are obtained as the tanning agent.Analysis gives the following values:

Solids content: 43.7%

Tanning agents: 27.4%

Substances other than tanning agents: 16.3%

Percentage of tanning agents in the total solids: 62.7

EXAMPLE 2

A mixture of 308 parts of 94% strength sulphuric acid and 416 parts of20% strength oleum (corresponding to 7.38 mols of sulphuric acid) areallowed to run rapidly into 518 parts (3.04 mols) of diphenyl ether. Thetemperature rises to about 110° C. 240 parts (2.55 mols) of moltenphenol are then also added to the sulphonation mixture. The mixture isnow kept at 125° C. for 2 hours. The mixture is sulphonic acids is thenheated to 150° C. under 15 mm Hg until the acid titre no longer changesand is 4.6; this takes 2 to 3 hours. 1,280 parts of the mixture ofsulphonic acids are obtained.

200 parts of the abovementioned mixture of sulphonic acids are mixedwith 40 parts of water and dissolved at 80° C. A solution of 15 parts ofurea in 50 parts of a 30% strength aqueous solution of formaldehyde arenow allowed to run in at this temperature at a rate such that thetemperature remains within 80° to 85° C. After all of the formaldehydesolution has run in, the condensation reaction is continued for afurther 6 hours. The viscous solution is diluted with 110 parts ofwater, the pH is adjusted to 4.0 with 82 parts of an aqueous 25%strength solution of ammonia and 12 parts of an 85% strength formic acidare then added. 509 parts of a pale brown viscous syrup which dissolvesin water to give a clear solution are obtained as the tanning agent.Analysis to determine the tanning agent content gives the followingvalues:

Solids content: 47.7%

Tanning agents: 31.8%

Substances other than tanning agents: 15.9%

Percentage of tanning agents in the total solids: 66.7

A product which has the same properties is obtained when a solution of30 parts of dimethylolurea in 40 parts of water is employed in place ofthe solution of 15 parts of urea in 50 parts of a 30% strength aqueoussolution of formaldehyde.

EXAMPLE 3

A mixture of 700 parts of ditolyl ether (3.53 mols of a mixture ofisomers) and 300 parts (3.19 mols) of phenol is sulphonated with 860parts (8.76 mols) of sulphuric acid monohydrate for 2 hours at 130° C.The resulting mixture of sulphonic acids is now heated to 145° C. under12 to 15 mm Hg until the acid titre is 4.4 and no longer decreases; thistakes 3 to 4 hours. 1,640 parts of the mixture of sulphonic acids areobtained.

100 parts of this mixture of sulphonic acids are melted with 20 parts ofwater and 6 parts of urea are added. 20 parts of a 30% strength aqueoussolution of formaldehyde are now allowed to run in dropwise at 90° to95° C. After all of the formaldehyde solution has run in, thecondensation reaction is carried out for 3 hours at 95° to 98° C. Afteradding 73 parts of water, the pH of the reaction mixture is adjusted to4.0 with 36 parts of a 25% strength aqueous solution of ammonia and 6parts of an 85% strength formic acid are then added.

260 parts of a pale brown syrup which dissolves in water to give a clearsolution are obtained as the tanning agent and analysis thereof givesthe following values:

Solids content: 47.3%

Tanning agents: 33.6%

Substances other than tanning agents: 13.7%

Percentage of tanning agents in the total solids: 70.9

EXAMPLE 4

25 parts of water are added to 100 parts of the condensed sulphonic acidmixture prepared according to Example 3 and the mixture is melted at 60°to 65° C. After adding 3 parts of urea, 8.1 parts of a 37% strengthaqueous solution of formaldehyde is added dropwise at 60° to 65° C. Thecondensation reaction is then continued for 3 hours at 60° to 65° C.

After adding 50 parts of water, the pH of the reaction mixture isadjusted to 4.5 with a 30% strength aqueous solution of sodium hydroxideand 3 parts of oxalic acid are then added. After evaporating thereaction solution under reduced pressure, 120 parts of a pale brown,water-soluble tanning agent powder are obtained.

Analysis to determine the tanning agent content gives the followingvalues:

Solids content: 92.9%

Tanning agents: 56.3%

Substances other than tanning agents: 36.6%

Percentage of tanning agents in the total solids: 60.6

EXAMPLE 5

100 parts of the condensed sulphonic acid mixture prepared according toExample 1 are melted with 20 parts of water at 80° C. After adding 12parts of urea, the solution is cooled to 60° C. and 40 parts of a 30%strength aqueous solution of formaldehyde are added at a rate such thatthe temperature does not rise above 65° C. The subsequent condensationreaction takes 15 hours at 60° to 65° C.

The viscous reaction solution is diluted with 80 parts of water and thepH is adjusted to 3.5 with 105 parts of a 30% strength aqueous solutionof potassium hydroxide and then to 3.2 with 6 parts of an 80% strengthacetic acid.

360 parts of a pale brown, viscous syrup which dissolves in water togive a clear solution are obtained. Analysis gives the following result:

Solids content: 38.2%

Tanning agents: 25.2%

Substances other than tanning agents: 13.0%

Percentage of tanning agents in the total solids: 66.0

EXAMPLE 6

604 parts of ditolyl ether (3.05 mols of a mixture of isomers) and 724parts (7.38 mols) of sulphuric acid monohydrate are mixed. Thetemperature rises to about 100° C. The reaction mixture is kept at thistemperature for one hour and 272 parts of a mixture of about 40% ofm-cresol and about 60% of p-cresol (2.51 mols of the mixture of isomers)are then added. A sulphonation reaction is now carried out for 2 hoursat 125° C. The mixture of sulphonic acids is heated to 145° C. and keptat this temperature for 5 hours under 12 mm Hg. After this time the acidtitre remains constant and is 4.4. 1,405 parts of the mixture ofsulphonic acids are obtained.

100 parts of the above mixture of sulphonic acids are brought intosolution with 20 parts of water and 4.5 parts of urea at 80° C. 15 partsof a 30% strength aqueous solution of formaldehyde are now addeddropwise at 80° to 95° C. After all of the formaldehyde solution has runin, the condensation reaction is continued for a further 3 hours. Afterdilution with 67 parts of water; the pH of the reaction solution isadjusted to 4.0 with 42 parts of a 25% strength aqueous solution ofammonia and then to 3.1 with an 85% strength formic acid. The resultingtanning agent (255 parts) in a brown solution which is miscible withwater in all proportions.

Analysis to determine the tanning agent content gives the followingvalues:

Solids content: 46.2%

Tanning agents: 31.5%

Substances other than tanning agents: 14.7%

Percentage of tanning agents in the total solids: 68.2

EXAMPLE 7

A mixture of 400 parts (4.25 mols) of phenol and 600 parts of ditolylether (3.03 mols of a mixture of isomers) is sulphonated with 1,000parts (10.2 mols) of sulphuric acid monohydrate for one hour at 120° C.The mixture of sulphonic acids is then heated to 170° C. under 15 mm Hgand kept at this temperature until the acid titre is 4.5 and no longerdecreases; this takes 3 hours. 1,738 parts of the mixture of sulphonicacids are obtained.

100 parts of the mixture of sulphonic acids are dissolved in 35 parts ofwater and 6 parts of urea at 80° C. 6 parts of paraformaldehyde areadded in small portions in the course of 20 minutes. The reactionsolution is then warmed to 90° to 95° C. and kept at this temperaturefor 21/2 hours. After diluting with 50 parts of water, the pH of thereaction solution is adjusted to 3.8 with 38 parts of a 25% strengthaqueous solution of ammonia and 6 parts of 85% strength formic acid arethen added.

The resulting tanning agent (225 parts) is a pale brown, viscous syrupwhich dissolves in water to give a clear solution and gives thefollowing values on analysis to determine the tanning agent content:

Solids content: 51.0%

Tanning agents: 38.1%

Substances other than tanning agents: 12.9%

Percentage of tanning agents in the total solids: 74.7

EXAMPLE 8

20 parts of water and 6 parts of urea are added to 100 parts of themixtue of sulphonic acids prepared according to Example 7 and themixture is warmed to 80° C. 20 parts of a 30% strength aqueous solutionof formaldehyde are now added at a rate such that the temperature risesto 90° to 95° C. The condensation reaction is brought to completion atthis temperature and this takes about 21/2 hours.

After diluting with 50 parts of water, the pH of the reaction solutionis adjusted to 4.2 with a 30% strength aqueous solution of sodiumhydroxide and 10 parts of maleic acid are then added. After drying underreduced pressure at 80° C., 130 parts of a pale brown powder whichdissolves in water to give a clear solution are obtained.

Analysis gives the following values:

Solids content: 97.8%

Tanning agents: 61.9%

Substances other than tanning agents: 35.9%

Percentage of tanning agents in the total solids: 63.6

EXAMPLE 9

900 parts (4.54 mols) of ditolyl ether (mixture of isomers) and 100parts (1.06 mols) of phenol are mixed and sulphonated with 700 parts(7.14 mols) of sulphuric acid monohydrate for 2 hours at 130° C. Themixture of sulphonic acids is warmed to 155° C. under 12 mm Hg and keptat this temperature for 3 hours. After this time the acid titre nolonger decreases and is 3.4. 1,510 parts of the mixture of sulphonicacids are obtained.

100 parts of the above mixture of sulphonic acids are melted in 25 partsof water at 80° C. 4.5 parts of urea are then added to this mixture. 15parts of a 30% strength aqueous solution of formaldehyde are allowed torun dropwise into the homogeneous solution at a rate such that thetemperature does not rise above 85° C. After the addition has ended, thecondensation reaction is continued for a further 4 hours at 80° to 85°C. After diluting with 80 parts of water, the pH of the reactionsolution is adjusted to 3.6 with 21 parts of ethanolamine and 7 parts oflactic acid are then added.

The resulting tanning agent (220 parts) is a pale brown, viscous syrupwhich dissolves in water to give a clear solution and gives thefollowing values on analysis:

Solids content: 54.5%

Tanning agents: 38.3%

Substances other than tanning agents: 16.2%

Percentage of tanning agents in the total solids: 70.2

EXAMPLE 10

100 parts of the mixture of sulphonic acids prepared according toExample 9 are dissolved in 25 parts of water at 90° to 95° C. 20 partsof a 30% strength aqueous solution of formaldehyde are added dropwise atthis temperature and after the addition has ended the condensationreaction is continued for a further 21/2 hours. After diluting with 50parts of water, the pH of the reaction solution is adjusted to 4.0 with39 parts of a 25% strength aqueous solution of ammonia and a mixture of7 parts of an 85% strength formic acid and 7 parts of an 80% strengthacetic acid is then added.

240 parts of a pale syrup which flows readily and dissolves in water togive a clear solution are obtained as the tanning agent. Analysis givesthe following result:

Solids content: 47.9%

Tanning agents: 34.3%

Substances other than tanning agents: 13.6%

Percentage of tanning agents in the total solids: 71.6

EXAMPLE 11

584 parts of ditolyl ether (2.94 mols of a mixture of isomers) are mixedwith 724 parts (7.38 mols) of sulphuric acid monohydrate and the mixtureis heated to 130° C. 262 parts (2.78 mols) of molten phenol are added tothe homogeneous mixture and the mixture is sulphonated for 2 hours. Themixture of sulphonic acids is heated to 150° C. under 15 mm Hg until theacid titre is 4.2 and no longer decreases; this takes 4 hours. 1,370parts of the mixture of sulphonic acids are obtained.

100 parts of the above mixture of sulphonic acids are dissolved in 25parts of water at 80° C. A mixture of 3 parts of urea and 3 parts ofbiuret is added to this solution. 20 parts of a 30% strength aqueoussolution of formaldehyde are allowed to run dropwise into the solutionat 80° to 85° C. After 5 hours the condensation reaction has ended. Forworking-up, 50 parts of water are added and the pH of the reactionsolution is adjusted to 6.0 with a 25% strength aqueous solution ofammonia. The solution is evaporated to dryness at 80° C. under reducedpressure.

115 parts of a pale brown powder which dissolves in water to give aclear solution are obtained.

Analysis to determine the tanning agent content, after adjusting the pHof the solution for analysis to 3.5 with formic acid, gives thefollowing values:

Solids content: 99.9%

Tanning agents: 83.7%

Substances other than tanning agents: 16.2%

Percentage of tanning agents in the total solids: 83.8

A product which ha virtually the same properties is obtained when 6parts of thiourea or 6.8 parts of ethyleneurea are employed in place ofthe urea/biuret mixture.

EXAMPLE 12

A mixture of 300 parts of ditolyl ether (1.76 mols of a mixture ofisomers) and 200 parts (2.12 mols) of phenol is sulphonated with 570parts (5.82 mols) of sulphuric acid monohydrate for 2 hours at 130° C.The resulting mixture of sulphonic acids is now heated to 145° C. underabout 14 mm Hg and kept at this temperature until the acid titre nolonger decreases (titre=5.2); this takes about 5 hours.

930 parts of the mixture of sulphonic acids are obtained.

300 parts of this mixture of sulphonic acids are dissolved in 60 partsof water at 80° C. After adding 27 parts of urea, 45 parts of a 30%strength aqueous solution of formaldehyde are added dropwise at such arate that a temperature of 80° to 85° C. is maintained. The condensationreaction is continued at this temperature for 5 hours. After dilutingwith 100 parts of water, the pH of the reaction mixture is adjusted to4.0 with 133 parts of a 48% strength solution of sodium hydroxide andthe mixture is then evaporated to dryness at 70° to 80° C. under reducedpressure.

370 parts of a pale brown powder which dissolves in water to give aclear solution are obtained.

Analysis to determine the tanning agent content, after adjusting the pHof the solution for analysis to 3.2 with formic acid, gives thefollowing values:

Solids content: 99.6%

Tanning agents: 55.3%

Substances other than tanning agents: 44.3%

Percentage of tanning agents in the total solids: 55.5

EXAMPLE 13

100 parts of the mixture of sulphonic acids obtained according toExample 12 are mixed with 20 parts of water and 3 parts of urea anddissolved at 75° C. 15 parts of a 30% strength aqueous solution offormaldehyde are now allowed to run in dropwise at 85° to 90° C. Afterthe addition has ended, the condensation reaction is continued for afurther 4 hours. After diluting with 50 parts of water, the pH of thereaction solution is adjusted to 3.8 with 44 parts of a 25% strengthaqueous solution of ammonia and then to 3.5 with 6 parts of an 80%strength acetic acid.

225 parts of a pale brown syrup which flows readily and readilydissolves in water are obtained. Analysis gives the following values:

Solids content: 50.3%

Tanning agents: 28.4%

Substances other than tanning agents: 21.9%

Percentage of tanning agents in the total solids: 56.5

EXAMPLE 14

125 parts of ditolyl ether (0.63 mol of a mixture of isomers) and 125parts (0.73 mol) of diphenyl ether are initially introduced and 396parts of 20% oleum (corresponding to 4.22 mols of sulphuric acid) areadded at such a rate that the temperature does not rise above 80° C. 250parts (2.65 mols) of molten phenol are poured into the homogeneousmixture and the mixture is heated rapidly to 135° C. The sulphonationreaction is carried out for 2 hours at this temperature.

The mixture of sulphonic acids is then heated to 160° C. under a reducedpressure of 15 mm Hg for 4 hours. After this time the acid titre is 3.5and no longer changes.

770 parts of the mixture of sulphonic acids are obtained.

100 parts of the above mixture of sulphonic acids are dissolved in 25parts of water at 80° C. After adding 9 parts of urea, 12.2 parts of a37% strength aqueous solution of formaldehyde are then allowed to run indropwise. The condensation reaction is continued for a further 4 hoursat 80° to 85° C. After diluting with 50 parts of water, the pH of thereaction mixture is adjusted to 4.0 with 50 parts of a 30% strengthaqueous solution of sodium hydroxide and then to 3.2 with 1.5 parts ofan 85% strength formic acid.

This gives 245 parts of a pale brown syrup which dissolves in water togive a clear solution and gives the following values on analysis:

Solids content: 49.7%

Tanning agents: 33.0%

Substances other than tanning agents: 16.7%

Percentage of tanning agents in the total solids: 66.4

EXAMPLE 15

100 parts of the mixture of sulphonic acids according to Example 3 aremelted with 20 parts of water and 6 parts of urea are added. 20 parts ofa 30% strength aqueous solution of formaldehyde are now allowed to runin dropwise at 90° to 95° C. After all of the formaldehyde solution hasrun in, the condensation reaction is carried out for 3 hours at 95° to98° C. After adding 25 parts of water, the pH of the reaction mixture isadjusted to 6.0 with 40 parts of a 25% strength aqueous solution ofammonia and the mixture is then evaporated to dryness at 80° C. underreduced pressure.

118 parts of a pale brown powder which dissolves in water to give aclear solution are obtained.

Analysis to determine the tanning agent content, after adjusting the pHof the solution for analysis to 3.2 with formic acid, gives thefollowing values:

Solids content: 97.7%

Tanning agents: 72.5%

Substances other than tanning agents: 25.2%

Percentage of tanning agents in the total solids: 74.2

EXAMPLE 16

100 parts of the mixture of sulphonic acids according to Example 3 aremelted with 20 parts of water and 6 parts of urea are added. 20 parts ofa 30% strength aqueous solution of formaldehyde are now allowed to runin dropwise at 90° to 95° C. After all of the formaldehyde solution hasrun in, the condensation reaction is carried out for 3 hours at 95° to98° C. After adding 25 parts of water, the pH of the reaction mixture isadjusted to 6.0 with 40 parts of a 25% strength aqueous solution ofammonia and the resulting mixture is then mixed with 70 parts of aneutral, 50% strength, aqueous solution of glutin glue. The homogeneousmixture is then dried.

This gives 166 parts of a pale brown, water-soluble powder which, as atanning agent, has a particularly good filling effect.

EXAMPLE 17

100 parts of a chrome-tanned calf leather which has been neutralised inthe customary manner are re-tanned for 2 hours with a solutionconsisting of 150 parts of water and 4 parts (parts calculated relativeto dry substance) of a tanning agent according to one of Examples 1 to10, 13 or 14.

After rinsing briefly, the re-tanned leather is stuffed, in thecustomary manner, using 4 to 6 parts of a stuffing agent which is fastto light and which is based on sulphonated sperm oil and the leather isthen dried.

This gives a leather which has a pale colour coupled with outstandingfastness to light and has a fine close grain.

EXAMPLE 18

100 parts of a delimed calf pelt are tanned for 24 hours with 200 partsof water and 24 parts (parts calculated relative to dry substance) of atanning agent according to one of Examples 2 to 8, 13 or 14.

After stuffing and working-up, a white leather which is fast to lightand of good firmness and has a fine compact grain is obtained.

EXAMPLE 19

100 parts of chrome-tanned heifer flanks which have been neutralised inthe customary manner are re-tanned for 11/2 hours with 200 parts ofwater and 5 parts (parts calculated relative to dry substance) of atanning agent according to one of Examples 2 to 9. After stuffing anddrying, a leather which has a very pale colour coupled with excellentfastness to light and a very favourable composite grain is obtained.

EXAMPLE 20

100 parts of a leather which has been chrome-tanned in the customarymanner and has not been neutralised are re-tanned for 21/2 hours with asolution consisting of 100 parts of water and 5 parts of the tanningagent according to one of Examples 11, 12, 15 and 16.

After stuffing and drying, a leather which has a pale colour and acompact fibre structure, in addition to a fine and firm grain, isobtained.

I claim:
 1. A sulphonated, aromatic reaction product of(1) 100 parts byweight of a sulphonation product of (A) 10 to 90 percent by weight of anunsubstituted diphenyl ether or of a diphenyl ether which is substitutedby methyl,(B) 90 to 10 percent by weight of an unsubstituted phenol, orof a phenol which is substituted by methyl, the sum of components (A)and (B) being 1 mol. and (C) 1 to 2 mols, calculated as sulphonic acid,of a sulphonating agent and (2) 4 to 24 parts by weight of a reactionmixture consisting of(D) an aminoplast-forming agent and (E)formaldehyde or a formaldehyde releasing agent, or (3) 4 to 24 parts byweight of an aminoplast precondensate, said aromatic reaction productbeing produced by a process, which comprises reacting components (A),(B) and (C) simultaneously at 110° to 180° C. or initially reactingcomponent (A) with component (C) at 110° to 120° C. and then withcomponent (B) at 110° to 180° C. or initially reacting component (B)with component (C) at 110° to 120° C. and then with component (A) at110° to 180° C. to give the sulphonation product (1), further reactingsaid sulphonation product (1) at a temperature from 60° to 95° C. withcomponents (2) or (3) to give a reaction product, then adding an organicor inorganic base to said reaction product and finally optionally addingan organic acid to said reaction product.
 2. A reaction productaccording to claim 1, which is obtained from 100 parts by weight ofcomponent (1) and 9 to 15 parts by weight of component (2) or (3).
 3. Areaction product according to claim 1, in which component (2) consistsof 1 mol of component (D) and 1 to 3 mols of component (E).
 4. Areaction product according to claim 1, in which component (3) consistsof a mono-, di- or trimethylolated aminoplast precondensate.
 5. Areaction product according to claim 1, in which component (A) consistsof diphenyl ether or a ditolyl ether.
 6. A reaction product according toclaim 1, in which component (B) consits of a cresol or of phenol.
 7. Areaction product according to claim 1, in which component (C) consistsof oleum or sulphuric acid monohydrate.
 8. A reaction product accordingto claim 1, in which component (E) consist of paraformaldehyde or of anaqueous solution of formaldehyde.
 9. A reaction product according toclaim 1, in which component (D) consists of thiourea, ethyleneurea,biuret or urea.
 10. A reaction product according to claim 1, in whichcomponent (3) consists of dimethylolated thiourea, ethyleneurea, biuretor urea.
 11. A process for the manufacture of a reaction productaccording to claim 1, in which(1) 100 parts by weight of a sulphonationproduct of (A) 10 to 90 percent by weight of an unsubstituted diphenylether or of a diphenylether which is substituted by methyl,(B) 90 to 10percent by weight of an unsubstituted phenol, or of a phenol which issubstituted by methyl, the sum of components (A) and (B) being 1 mol,and (C) 1 to 2 mole, calculated as sulphuric acid, of a sulphonatingagent; components (A), (B) and (C) first being reacted with one anotherat temperature from 110° to 180° C. to give the sulphonation product(1); are further reacted at temperature from 60° to 95° C. with (2) 4 to24 parts by weight of a reaction mixture consisting of(D) anaminoplast-forming agent and (E) formaldehyde or a formaldehydereleasing agent, or (3) 4 to 24 parts by weight of an aminoplastprecondensate; and an organic or inorganic base is added to theresulting reaction product and an organic acid is then optionally added.12. A process for tanning or re-tanning hides or chrome-tanned leather,in which hides or leather are treated with an aqueous solutioncontaining a reaction product according to claim 1 and the materialtanned in this way is rinsed and subsequently stuffed and dried.
 13. Thehides which have been tanned, or leather which has been re-tanned, bythe process according to claim
 12. 14. An agent for tanning hides or forre-tanning leather which contains a reaction product having thecomposition indicated in claim
 1. 15. A reaction product according toclaim 1, wherein components (A), (B) and (C) are reacted at an initialtemperature from 110° C. to 140° C. and then the temperature of thereaction is raised to 145° to 170° C.
 16. A reaction product accordingto claim 1, wherein components (A), (B) and (C) are reacted at aninitial temperature from 120° C. to 135° C. and then the temperature ofthe reaction is raised to 145° to 170° C.